On Nov. 20, 2006, former Philadelphia Eagles safety Andre Waters shot himself in the head at his house in Tampa.

Though he was only 44 when he died, his brain looked more like that of someone decades older who was suffering from dementia, according to the doctor who examined him.

Dave Duerson, a safety for the Chicago Bears in the 1980’s, shot himself in the chest in his apartment in Florida on Feb. 17, 2011. Before killing himself, Duerson requested that his brain be studied for chronic traumatic encephalopathy, a disease that kills brain cells and is linked to repeated head trauma. His brain showed signs of the condition.

In April of the next year, Ray Easterling, a former Atlanta Falcon, shot himself in his house in Richmond, Va. His brain also showed signs of CTE.

Two weeks later, former San Diego Chargers linebacker Junior Seau shot himself in the chest at his home in Oceanside, Ca. CTE showed up in his brain.

Though the four former NFL players cannot argue that the league misled them about the depression, mood swings and memory loss they endured, their loved ones can.

The estates of the four suicide victims, along with more than 4,000 other former players, are suing the NFL for neglecting to tell players about the dangers of blows to the head and hiding evidence that linked head trauma with long-term brain damage. The plaintiffs are demanding damages and a medical monitoring program that will aid players in the event they experience symptoms of brain damage.

The league has denied the claims, and argued to dismiss the suit on the grounds that it should be decided through arbitration.

“The NFL has long made player safety a priority and continues to do so,” the league said in a statement. “Any allegation that the NFL intentionally sought to mislead players has no merit. It stands in contrast to the league’s actions to better protect players and advance the science and medical understanding of the management and treatment of concussions.”

(Read the stories of the players profiled by Columbia University’s sports journalism students.)

The first concussion-related lawsuit was filed in July 2011 and included 75 former players and 51 spouses. 85 lawsuits were consolidated into a master complaint in June 2012 in the Eastern District of Pennsylvania. More suits were filed since then to give the case its current figure of more than 4,000 plaintiffs.

Judge Anita B. Brody heard arguments on April 9 in Philadelphia. Brody, a graduate of Columbia Law School, will decide whether the case will move forward in her court or go through arbitration, which the NFL lawyers support.

Some players are clearly experiencing the long-term effects of several years’ worth of hits. Kevin Turner, who played fullback from 1992-99 with the New England Patriots and Philadelphia Eagles, is suffering from amyotrophic lateral sclerosis, which has robbed him of strength in his arms and hands and the ability to do mundane tasks without help. He said he believes the punishing headshots he took while playing contributed to the condition. Dr. Ann McKee, who co-founded the Center for the Study of Traumatic Encephalopathy at Boston University, said in March 2011 that NFL players are eight to ten times more likely to develop ALS than an average person. Turner said he spoke to McKee about two years ago regarding his diagnosis.

“From what I gathered talking to [McKee], she felt extremely confident that not only my case but several others were caused by head trauma or brain injuries,” Turner said. Turner and several other NFL players have decided to donate their brains to McKee’s study after they die.

Some plaintiffs do not show any signs of brain damage, but they can still sue because the suit seeks medical treatment for all former players in case any health problems arise in the future, according to legal sources with knowledge of the case.

In his argument in Brody’s court, David Frederick, who represents the players, argued that the NFL made itself “the guarantor of player safety” as far back as the 1920’s when pro football began. He said that meant the league gave itself the responsibility to protect players, and it subsequently breached that duty. Among those breaches, Frederick argued, was negligence in the form of failing to warn active and retired players of the dangers of concussive and sub-concussive head trauma. He also argued that the NFL’s Mild Traumatic Brain Injury committee, created in 1994, continued giving misleading information by claiming there was no connection between head trauma and future brain damage. As recently as 2007, the league gave a pamphlet to players that said having more than one or two concussions would not cause future damage if they were properly treated. Additionally, the plaintiffs accused the NFL of simultaneously taking on the responsibility of protecting its players while also marketing and profiting from the league’s most violent hits, which were repeatedly shown in videos, produced by NFL Films, which is owned by the league.

In addition to its denying the charges, the NFL also argued that the case should not move forward in Brody’s court because it falls under the league’s collective bargaining agreement. In his April 9 argument, NFL lawyer Paul Clement claimed the case should move to arbitration based on Section 301 of the Labor Management Relations Act, a federal act that says cases that require interpretation of a collective bargaining agreement should be solved through arbitration.

Clement claimed that issues of player safety are mentioned in the CBA between the league and the players, meaning interpretation of the agreement is required.

If Brody rules the case should stay in her court, it will move to a long discovery phase in which the two sides will gather information for later use.

The issue of concussions has already led to a vigorous debate – and to rules changes. Helmet-to-helmet hits are more strictly enforced and kickoffs have been moved up to the 35-yard line in an effort to make the game safer. Concussions are now being discussed at length, and for Turner, that is progress.

“Regardless of what judge Brody deems appropriate I think at least through the last three years the NFL has had to take notice of some of the people that were involved,” Turner said. “And they’ve had to change their tune as far as brain injury or head trauma is concerned.”